Environmental Engineering Reference
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Figure 11.20: Electrolytic cell for carrying out electrorefining [From ref. 672 . Reprinted with
permission].
Ni, and V, reached 90, 99, and 99%, respectively. When this acid leachate was electrolyzed for
2 h at 2 A constant current (current density =
35.7mA/cm 2 ), the electrolytic recoveries of
Mo, Ni, and V were 15, 61, and 66%, respectively. Extending the electrolysis time from 2 to
4 h did not increase the recoveries. For this operation, the total recoveries (leaching yield x
electrolytic recovery) of Mo, Ni, and V were around 14, 60, and 65%, respectively.
11.1.6 Metal Recovery by Applying Thermal Plasma
Recently, a process for recovery and reduction of metals (Co and Mo) from spent
hydroprocessing catalysts by thermal plasma was developed by Wong et al. [676] . In this
process, the spent catalyst was first sintered at > 1500 K under plasma conditions and Co-Mo
oxide was reduced to Co-Mo. This was confirmed by spectroscopic techniques. The coke
 
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